Added power saving mode

docs/TODO.txt

@@ -342,7 +342,6 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - inputs: add mouse cursor for unavailable/no? IDC_NO/SDL_SYSTEM_CURSOR_NO.
  - inputs/scrolling: support for smooth scrolling (#2462, #2569)
 
- - misc: idle: expose "woken up" boolean (set by inputs) and/or animation time (for cursor blink) for back-end to be able stop refreshing easily.
  - misc: idle: if cursor blink if the _only_ visible animation, core imgui could rewrite vertex alpha to avoid CPU pass on ImGui:: calls.
  - misc: idle: if cursor blink if the _only_ visible animation, could even expose a dirty rectangle that optionally can be leverage by some app to render in a smaller viewport, getting rid of much pixel shading cost.
  - misc: make the ImGuiCond values linear (non-power-of-two). internal storage for ImGuiWindow can use integers to combine into flags (Why?)
@@ -363,9 +362,7 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - demo: add virtual scrolling example?
  - demo: demonstrate Plot offset
  - examples: window minimize, maximize (#583)
- - examples: provide a zero frame-rate/idle example.
  - examples: apple: example_apple should be using modern GL3.
- - examples: glfw: could go idle when minimized? if (glfwGetWindowAttrib(window, GLFW_ICONIFIED)) { glfwWaitEvents(); continue; } // issue: DeltaTime will be super high on resume, perhaps provide a way to let impl know (#440)
  - examples: opengl: rename imgui_impl_opengl2 to impl_opengl_legacy and imgui_impl_opengl3 to imgui_impl_opengl? (#1900)
  - examples: opengl: could use a single vertex buffer and glBufferSubData for uploads?
  - examples: opengl: explicitly disable GL_STENCIL_TEST in bindings.

examples/example_allegro5/main.cpp

@@ -63,6 +63,7 @@ int main(int, char**)
         // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
         // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
         // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
+        ImGui_ImplAllegro5_WaitForEvent(queue);
         ALLEGRO_EVENT ev;
         while (al_get_next_event(queue, &ev))
         {
@@ -105,6 +106,7 @@ int main(int, char**)
             ImGui::Text("counter = %d", counter);
 
             ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+            ImGui::Text("Frames since last input: %d", ImGui::GetIO().FrameCountSinceLastInput);
             ImGui::End();
         }
 

examples/example_glfw_opengl3/main.cpp

@@ -126,6 +126,7 @@ int main(int, char**)
         // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
         // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
         // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
+        ImGui_ImplGlfw_WaitForEvent();
         glfwPollEvents();
 
         // Start the Dear ImGui frame
@@ -157,6 +158,7 @@ int main(int, char**)
             ImGui::Text("counter = %d", counter);
 
             ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+            ImGui::Text("Frames since last input: %d", ImGui::GetIO().FrameCountSinceLastInput);
             ImGui::End();
         }
 

examples/example_sdl_opengl3/main.cpp

@@ -120,6 +120,7 @@ int main(int, char**)
         // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
         // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
         // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
+        ImGui_ImplSDL2_WaitForEvent();
         SDL_Event event;
         while (SDL_PollEvent(&event))
         {
@@ -159,6 +160,7 @@ int main(int, char**)
             ImGui::Text("counter = %d", counter);
 
             ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+            ImGui::Text("Frames since last input: %d", ImGui::GetIO().FrameCountSinceLastInput);
             ImGui::End();
         }
 

examples/example_win32_directx11/main.cpp

@@ -80,18 +80,22 @@ int main(int, char**)
     // Main loop
     MSG msg;
     ZeroMemory(&msg, sizeof(msg));
-    while (msg.message != WM_QUIT)
+    bool done = false;
+    while (!done)
     {
         // Poll and handle messages (inputs, window resize, etc.)
         // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
         // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
         // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
         // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
-        if (::PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE))
+        ImGui_ImplWin32_WaitForEvent();
+        while (::PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE))
         {
             ::TranslateMessage(&msg);
             ::DispatchMessage(&msg);
-            continue;
+
+            if (msg.message == WM_QUIT)
+                done = true;
         }
 
         // Start the Dear ImGui frame
@@ -123,6 +127,7 @@ int main(int, char**)
             ImGui::Text("counter = %d", counter);
 
             ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+            ImGui::Text("Frames since last input: %d", ImGui::GetIO().FrameCountSinceLastInput);
             ImGui::End();
         }
 

examples/imgui_impl_allegro5.cpp

@@ -32,6 +32,7 @@
 
 #include <stdint.h>     // uint64_t
 #include <cstring>      // memcpy
+#include <math.h>       // isinf
 #include "imgui.h"
 #include "imgui_impl_allegro5.h"
 
@@ -317,6 +318,24 @@ void ImGui_ImplAllegro5_Shutdown()
     g_ClipboardTextData = NULL;
 }
 
+void ImGui_ImplAllegro5_WaitForEvent(ALLEGRO_EVENT_QUEUE* queue)
+{
+    if (!(ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_EnablePowerSavingMode))
+        return;
+
+    int display_flags = al_get_display_flags(g_Display);
+    bool window_is_hidden = display_flags & ALLEGRO_MINIMIZED;
+    double waiting_time = window_is_hidden ? INFINITY : ImGui::GetEventWaitingTime();
+    if (waiting_time > 0.0)
+    {
+        if (isinf(waiting_time))
+            al_wait_for_event(queue, NULL);
+        else
+            al_wait_for_event_timed(queue, NULL, waiting_time);
+    }
+}
+
+
 // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
 // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
 // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
@@ -325,6 +344,8 @@ bool ImGui_ImplAllegro5_ProcessEvent(ALLEGRO_EVENT *ev)
 {
     ImGuiIO& io = ImGui::GetIO();
 
+    io.FrameCountSinceLastInput = 0;
+
     switch (ev->type)
     {
     case ALLEGRO_EVENT_MOUSE_AXES:

examples/imgui_impl_allegro5.h

@@ -16,12 +16,14 @@
 #pragma once
 
 struct ALLEGRO_DISPLAY;
+struct ALLEGRO_EVENT_QUEUE;
 union ALLEGRO_EVENT;
 
 IMGUI_IMPL_API bool     ImGui_ImplAllegro5_Init(ALLEGRO_DISPLAY* display);
 IMGUI_IMPL_API void     ImGui_ImplAllegro5_Shutdown();
 IMGUI_IMPL_API void     ImGui_ImplAllegro5_NewFrame();
 IMGUI_IMPL_API void     ImGui_ImplAllegro5_RenderDrawData(ImDrawData* draw_data);
+IMGUI_IMPL_API void     ImGui_ImplAllegro5_WaitForEvent(ALLEGRO_EVENT_QUEUE* queue);
 IMGUI_IMPL_API bool     ImGui_ImplAllegro5_ProcessEvent(ALLEGRO_EVENT* event);
 
 // Use if you want to reset your rendering device without losing ImGui state.

examples/imgui_impl_glfw.cpp

@@ -37,6 +37,8 @@
 #include "imgui.h"
 #include "imgui_impl_glfw.h"
 
+#include <math.h> // isinf
+
 // GLFW
 #include <GLFW/glfw3.h>
 #ifdef _WIN32
@@ -66,6 +68,7 @@ static GLFWcursor*          g_MouseCursors[ImGuiMouseCursor_COUNT] = { 0 };
 // Chain GLFW callbacks: our callbacks will call the user's previously installed callbacks, if any.
 static GLFWmousebuttonfun   g_PrevUserCallbackMousebutton = NULL;
 static GLFWscrollfun        g_PrevUserCallbackScroll = NULL;
+static GLFWcursorposfun     g_PrevUserCallbackCursorPos = NULL;
 static GLFWkeyfun           g_PrevUserCallbackKey = NULL;
 static GLFWcharfun          g_PrevUserCallbackChar = NULL;
 
@@ -84,6 +87,9 @@ void ImGui_ImplGlfw_MouseButtonCallback(GLFWwindow* window, int button, int acti
     if (g_PrevUserCallbackMousebutton != NULL)
         g_PrevUserCallbackMousebutton(window, button, action, mods);
 
+    ImGuiIO& io = ImGui::GetIO();
+    io.FrameCountSinceLastInput = 0;
+
     if (action == GLFW_PRESS && button >= 0 && button < IM_ARRAYSIZE(g_MouseJustPressed))
         g_MouseJustPressed[button] = true;
 }
@@ -94,16 +100,31 @@ void ImGui_ImplGlfw_ScrollCallback(GLFWwindow* window, double xoffset, double yo
         g_PrevUserCallbackScroll(window, xoffset, yoffset);
 
     ImGuiIO& io = ImGui::GetIO();
+    io.FrameCountSinceLastInput = 0;
     io.MouseWheelH += (float)xoffset;
     io.MouseWheel += (float)yoffset;
 }
 
+void ImGui_ImplGlfw_CursorPosCallback(GLFWwindow* window, double xpos, double ypos)
+{
+    if (g_PrevUserCallbackCursorPos != NULL)
+        g_PrevUserCallbackCursorPos(window, xpos, ypos);
+
+    ImGuiIO& io = ImGui::GetIO();
+    io.FrameCountSinceLastInput = 0;
+
+    // Here, we just take note of the event without actually processing the cursor position.
+    // This is done in ImGui_ImplGlfw_NewFrame() / ImGui_ImplGlfw_UpdateMousePosAndButtons().
+}
+
 void ImGui_ImplGlfw_KeyCallback(GLFWwindow* window, int key, int scancode, int action, int mods)
 {
     if (g_PrevUserCallbackKey != NULL)
         g_PrevUserCallbackKey(window, key, scancode, action, mods);
 
     ImGuiIO& io = ImGui::GetIO();
+    io.FrameCountSinceLastInput = 0;
+
     if (action == GLFW_PRESS)
         io.KeysDown[key] = true;
     if (action == GLFW_RELEASE)
@@ -122,6 +143,7 @@ void ImGui_ImplGlfw_CharCallback(GLFWwindow* window, unsigned int c)
         g_PrevUserCallbackChar(window, c);
 
     ImGuiIO& io = ImGui::GetIO();
+    io.FrameCountSinceLastInput = 0;
     io.AddInputCharacter(c);
 }
 
@@ -185,6 +207,7 @@ static bool ImGui_ImplGlfw_Init(GLFWwindow* window, bool install_callbacks, Glfw
     {
         g_PrevUserCallbackMousebutton = glfwSetMouseButtonCallback(window, ImGui_ImplGlfw_MouseButtonCallback);
         g_PrevUserCallbackScroll = glfwSetScrollCallback(window, ImGui_ImplGlfw_ScrollCallback);
+        g_PrevUserCallbackCursorPos = glfwSetCursorPosCallback(window, ImGui_ImplGlfw_CursorPosCallback);
         g_PrevUserCallbackKey = glfwSetKeyCallback(window, ImGui_ImplGlfw_KeyCallback);
         g_PrevUserCallbackChar = glfwSetCharCallback(window, ImGui_ImplGlfw_CharCallback);
     }
@@ -213,6 +236,22 @@ void ImGui_ImplGlfw_Shutdown()
     g_ClientApi = GlfwClientApi_Unknown;
 }
 
+void ImGui_ImplGlfw_WaitForEvent()
+{
+    if (!(ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_EnablePowerSavingMode))
+        return;
+
+    bool window_is_hidden = !glfwGetWindowAttrib(g_Window, GLFW_VISIBLE) || glfwGetWindowAttrib(g_Window, GLFW_ICONIFIED);
+    double waiting_time = window_is_hidden ? INFINITY : ImGui::GetEventWaitingTime();
+    if (waiting_time > 0.0)
+    {
+        if (isinf(waiting_time))
+            glfwWaitEvents();
+        else
+            glfwWaitEventsTimeout(waiting_time);
+    }
+}
+
 static void ImGui_ImplGlfw_UpdateMousePosAndButtons()
 {
     // Update buttons

examples/imgui_impl_glfw.h

@@ -24,6 +24,7 @@ IMGUI_IMPL_API bool     ImGui_ImplGlfw_InitForOpenGL(GLFWwindow* window, bool in
 IMGUI_IMPL_API bool     ImGui_ImplGlfw_InitForVulkan(GLFWwindow* window, bool install_callbacks);
 IMGUI_IMPL_API void     ImGui_ImplGlfw_Shutdown();
 IMGUI_IMPL_API void     ImGui_ImplGlfw_NewFrame();
+IMGUI_IMPL_API void     ImGui_ImplGlfw_WaitForEvent();
 
 // InitXXX function with 'install_callbacks=true': install GLFW callbacks. They will call user's previously installed callbacks, if any.
 // InitXXX function with 'install_callbacks=false': do not install GLFW callbacks. You will need to call them yourself from your own GLFW callbacks.

examples/imgui_impl_sdl.cpp

@@ -50,6 +50,8 @@
 #include "TargetConditionals.h"
 #endif
 
+#include <math.h> // isinf
+
 #define SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE    SDL_VERSION_ATLEAST(2,0,4)
 #define SDL_HAS_VULKAN                      SDL_VERSION_ATLEAST(2,0,6)
 
@@ -73,6 +75,26 @@ static void ImGui_ImplSDL2_SetClipboardText(void*, const char* text)
     SDL_SetClipboardText(text);
 }
 
+void ImGui_ImplSDL2_WaitForEvent()
+{
+    if (!(ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_EnablePowerSavingMode))
+        return;
+
+    Uint32 window_flags = SDL_GetWindowFlags(g_Window);
+    bool window_is_hidden = window_flags & (SDL_WINDOW_HIDDEN | SDL_WINDOW_MINIMIZED);
+    double waiting_time = window_is_hidden ? INFINITY : ImGui::GetEventWaitingTime();
+    if (waiting_time > 0.0)
+    {
+        if (isinf(waiting_time))
+            SDL_WaitEvent(NULL);
+        else
+        {
+            const int waiting_time_ms = (int)(1000.0 * ImGui::GetEventWaitingTime());
+            SDL_WaitEventTimeout(NULL, waiting_time_ms);
+        }
+    }
+}
+
 // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
 // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
 // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
@@ -81,6 +103,8 @@ static void ImGui_ImplSDL2_SetClipboardText(void*, const char* text)
 bool ImGui_ImplSDL2_ProcessEvent(const SDL_Event* event)
 {
     ImGuiIO& io = ImGui::GetIO();
+    io.FrameCountSinceLastInput = 0;
+
     switch (event->type)
     {
     case SDL_MOUSEWHEEL:

examples/imgui_impl_sdl.h

@@ -24,4 +24,5 @@ IMGUI_IMPL_API bool     ImGui_ImplSDL2_InitForVulkan(SDL_Window* window);
 IMGUI_IMPL_API bool     ImGui_ImplSDL2_InitForD3D(SDL_Window* window);
 IMGUI_IMPL_API void     ImGui_ImplSDL2_Shutdown();
 IMGUI_IMPL_API void     ImGui_ImplSDL2_NewFrame(SDL_Window* window);
+IMGUI_IMPL_API void     ImGui_ImplSDL2_WaitForEvent();
 IMGUI_IMPL_API bool     ImGui_ImplSDL2_ProcessEvent(const SDL_Event* event);

examples/imgui_impl_win32.cpp

@@ -14,6 +14,7 @@
 #endif
 #include <windows.h>
 #include <XInput.h>
+#include <math.h> // isinf
 #include <tchar.h>
 
 // CHANGELOG
@@ -236,6 +237,20 @@ void    ImGui_ImplWin32_NewFrame()
     ImGui_ImplWin32_UpdateGamepads();
 }
 
+void ImGui_ImplWin32_WaitForEvent()
+{
+    if (!(ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_EnablePowerSavingMode))
+        return;
+
+    BOOL window_is_hidden = !IsWindowVisible(g_hWnd) || IsIconic(g_hWnd);
+    double waiting_time = window_is_hidden ? INFINITE : ImGui::GetEventWaitingTime();
+    if (waiting_time > 0.0)
+    {
+        DWORD waiting_time_ms = isinf(waiting_time) ? INFINITE : (DWORD)(1000.0 * waiting_time);
+        ::MsgWaitForMultipleObjectsEx(0, NULL, waiting_time_ms, QS_ALLINPUT, MWMO_INPUTAVAILABLE|MWMO_ALERTABLE);
+    }
+}
+
 // Allow compilation with old Windows SDK. MinGW doesn't have default _WIN32_WINNT/WINVER versions.
 #ifndef WM_MOUSEHWHEEL
 #define WM_MOUSEHWHEEL 0x020E
@@ -257,6 +272,9 @@ IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND hwnd, UINT msg, WPARA
         return 0;
 
     ImGuiIO& io = ImGui::GetIO();
+
+    io.FrameCountSinceLastInput = 0;
+
     switch (msg)
     {
     case WM_LBUTTONDOWN: case WM_LBUTTONDBLCLK:

examples/imgui_impl_win32.h

@@ -12,6 +12,7 @@
 IMGUI_IMPL_API bool     ImGui_ImplWin32_Init(void* hwnd);
 IMGUI_IMPL_API void     ImGui_ImplWin32_Shutdown();
 IMGUI_IMPL_API void     ImGui_ImplWin32_NewFrame();
+IMGUI_IMPL_API void     ImGui_ImplWin32_WaitForEvent();
 
 // Handler for Win32 messages, update mouse/keyboard data.
 // You may or not need this for your implementation, but it can serve as reference for handling inputs.